Hello,
It sure is duplicate content. By putting "/article.cfm" into the robot.txt won't work because if you do that you are just re-directing the whole folder. You need to do a permanent re-direct. I had a brief look at the site and it seems like there are over 1000+ pages. This might take a while but it is neccessary to do it, if not your clients rankings will not perform and most likely penalised. A simple way would be doing a canonical link in /article.cfm?intDocID=22572 so you are showing google the main article is located at /bc-blazes-construction-trail.
However, the best way would be doing a 301 permanent re-direct of course. I'm sure you could get a web dev to write a script to automatically run through the database and output the re-directs than manually re-directing 1000+ pages. If it can't be done, you could outsource it on freelancer.com for around $2-300.
Thanks